Atrial Fibrillation Clinical Guidelines: A Review of the Evidence Base

A recent review published in JAMA Cardiology revealed that despite an increase in atrial fibrillation (AF) research, clinical practice guideline updates could still be improved.¹

The American Heart Association/American College of Cardiology (AHA/ACC) first published the guidelines in 2001, with the Heart Rhythm Society (HRS) joining in 2011. These guidelines are widely used to direct patient care and have become the basis for a national performance initiative.² As such, the authors of the review sought to evaluate changes in the strength of the recommendations and quality of evidence, and to determine the areas in need of more research.

From 2001 to 2014, the total number of recommendations increased from 95 to 113. However, there were no statistically significant changes in the proportions of recommendations assigned to each Class of Recommendation (COR) or Level of Evidence (LOE). Specifically, LOE B increased from 30.5% to 39.8% while LOE C decreased from 60.0% to 51.3%; LOE A did not change significantly (8.4% to 8.8%). In fact, LOE A was the least common designation in the 2014 guideline; LOE C was the most common at 51.3%.

Meanwhile, the recommendations were split equally among class I and class IIa/IIb (43.4% each), with only 13.3% assigned to class III. By COR-LOE combination, II-B saw an increase from 11.6% to 20.4% and II-C decreased from 28.4% to 19.5%. The most common designations in the 2014 guideline were I-C (25.7%) and II-B (20.4%).

Use of level C evidence decreased, except in antithrombotic therapy; level B increased in all categories except miscellaneous and level A remained the same or increased in all categories except antithrombotic therapy.

Of note, rate control has not had any level A recommendations—a constant since the guidelines were first released in 2001. It also has the lowest proportion of class I recommendations (25%) of all AF categories. Antithrombotic therapy changes mostly occurred between 2011 and 2014, likely due to published data on non-vitamin K antagonist oral anticoagulants.

LOE has been downgraded in 6 of 21 recommendations and upgraded in 2 of 21. COR was not downgraded in any recommendations, but upgraded in 2 of 21.

The quality of evidence supporting the AF guidelines has improved—particularly in the decrease of LOE C and increase of LOE B, which the authors cited as “less of a reliance on expert consensus and a larger role of medium-quality clinical evidence.” The use of LOE A, however, is inconsistent with this trend—only 8.8% of all 2014 guidelines were supported by LOE A. “This is despite the large increase in the number of randomized trials on AF per year over this period,” the authors wrote, “indicating that these studies may not be of sufficient size or methodologic rigor, or address a pragmatic decision/treatment, to result in an LOE A guideline recommendation.”

The authors concluded that AF clinical guidelines are of great importance and that their findings underscore the need for more high-quality and targeted studies.

Study Limitations

• Revisions to aims and methodology used by the ACC/AHA/HRS were not taken into account.
• Clinical practice guidelines from the European Society of Cardiology and the American College of Chest Physicians were not included.
• Areas of AF evaluation and management not currently included in the guidelines were not considered in this review.

Disclosures: Dr Fonarow reports financial relationships with Janssen Pharmaceuticals, Medtronic, and St. Jude Medical. Dr Calkins reports financial relationships with Medtronic, Abbott Medical, and Boehringer Ingelheim. Dr Steinberg receives research support from Janssen Pharmaceuticals and Boston Scientific, provides consulting to BMS/Pfizer, and receives educational support from Medtronic and Biotronik. Dr Peterson reports financial relationships with AstraZeneca, Bayer Pharmaceuticals, Janssen Pharmaceuticals, Merck, Regeneron Pharmaceuticals, Sanofi-Aventis, and Valenat Pharmaceuticals. Dr Piccini receives research funding from Boston Scientific, Gilead Sciences, Janssen Pharmaceuticals, Johnson & Johnson, ResMed, Spectranetics, and St. Jude Medical, and consults for BMS/Pfizer, GalxoSmithKline, Janssen Pharmaceuticals, Johnson & Johnson, Medtronic, and Spectranetics.

References

1. Barnett AS, Lewis WR, Field ME, et al. Quality of evidence underlying the American Heart Association/American College of Cardiology/Heart Rhythm Society Guidelines on the management of atrial fibrillation [Published online December 14, 2016]. JAMA Cardiol. doi:10.1001/jamacardio.2016.4936.
2. Lewis WR, Piccini JP, Turakhia MP, et al. Get With The Guidelines AFIB: novel quality improvement registry for hospitalized patients with atrial fibrillation. Circ Cardiovasc Qual Outcomes. 2014;7(5):770-777.